#include <math.h>
#include <stdio.h>
double fun(int  n)
{
	int i;
	double s1=0,sum=0;
	for(i=1;i<=n;i++)
	{
		s1+=sqrt(i);
		sum+=s1;
	}
	return sum;
}
main()
{ int  n;    double  s;
  printf("\n\nInput n:  ");  scanf("%d",&n);
  s=fun(n);
  printf("\n\ns=%f\n\n",s);
}
